Append PDF to a Signed PDF

Question

I need to append a pdf file to a digital signed pdf file, keeping valid the signature ...maybe using revision? ...using iTextSharp? How can I do it?

Please help me with some sample.

Answer 1

You can't as that invalidates the whole point of digital signatures, namely to detect when something exactly as you describe occurs and therefore ensure the validity of the original document. To do as you want, you will need to add the extra PDF to the unsigned original PDF and then resign the new conglomerate PDF.

Answer 2

You can use Increment Update to do that, as long as the original signature allows you.

Take look at the document:

http://learn.adobe.com/wiki/download/attachments/52658564/Acrobat_DigitalSignatures_in_PDF.pdf?version=1&modificationDate=1269905473000

on Page 8 you will find what you want.